1. Field of the Invention
This invention relates to electrophoresis. More particularly, it relates to electrophoretic coating of small ware such as metal fasteners, particularly aluminum rivets, by conducting the same through a flowing coating medium.
2. Description of the Prior Art
Electrophoretic coating of small articles, as taught, for example, by U.S. Pat. No. 3,361,658, has become quite popular in recent years. Nevertheless, it has met with problems, for example, inconsistent and non-uniform painting or coating of odd-shaped or uneven-shaped objects, especially rounded objects such as metal fasteners which have rounded heads, including arcuate and semicircular or part circular contours when considered in cross section. By semicircular or part circular herein we refer to any surface which may comprise at least a portion of the circumference of a circle when viewed in a single plane. In electrophoretic coating, usually one or more moving belts or lines of the objects to be coated, electrically charged, pass beneath a nozzle, likewise but oppositely charged, through which the coating medium, for example, a polymer or copolymer is discharged. Any excess coating medium falling or removed from the objects being coated according to such a process may be conducted to a reservoir from which the coating material, usually in the form of an aqueous dispersion, may be passed to the nozzle. Unfortunately, however, the aforementioned problems of inconsistent and non-uniform or uneven coating are encountered when the coating material such as paint or lacquer is not applied uniformly, for example, where a rounded object is coated more thickly toward the center than toward the periphery or edge thereof.